1. Field of the Invention
The present invention relates to the field of communication networks. More particularly, the present invention relates to a system and method for distributing audio and video in a digital format throughout a vehicle.
2. Description of Art Related to the Invention
Over the last few decades, commercial aircraft has become a necessary mode of travel for personal and business reasons. In order to improve passenger comfort, many commercial airlines have implemented in-flight entertainment ("IFE") systems which offer on-board telephony as well as in-flight movies broadcasted at a preselected time.
Currently, the distribution of audio and video throughout a commercial aircraft is accomplished through the implementation of analog circuitry. More specifically, an audio/video source (e.g., a television tuner, video tape reproducers) is implemented on the aircraft to transfer both audio and video in analog form to a radio frequency ("RF") modulator. The audio is synchronized with the video by time bracketing a portion of audio with a particular frame of video.
The RF modulator converts the audio and video (collectively referred to as "media") from the audio/video source into a RF signal having a particular bandpass frequency. The RF signal is input into a combiner which is circuitry that combines several RF signals together to produce one analog signal. The analog signal is routed to an amplifier, and is subsequently distributed throughout the aircraft over coaxial cable. The coaxial cable enables the amplified analog signal to be sent to various drivers positioned at certain areas of the aircraft. These drivers propagate the amplified analog signal to a number of passenger seats. Each passenger seat includes a RF demodulator which is selectively tuned by the passenger to a particular RF frequency to be able to view the video and/or listen to the audio.
Recently, many commercial airlines are now in the process of implementing more advanced IFE systems which offer a greater variety of in-flight entertainment such as video games, pay-per-view movies, hotel reservations services, and the like. As a result, the conventional IFE system suffers from a number of architectural deficiencies. One deficiency is that the conventional IFE system requires RF modulation and demodulation circuitry which adds significant weight to the aircraft. It is well known that additional weight of the aircraft reduces its fuel economy.
A second deficiency associated with the conventional IFE system is that it possesses high movie startup latency characteristics and is incapable of supporting a large number (e.g., greater than twenty) of analog channels. In order for the conventional IFE system to provide both broadcast and actual "video on demand" services, namely the ability of each passenger to select playback of any video at any given time period as opposed to other prior systems that offer feature films at selected start increments, a greater number of analog channels are required. Although the conventional IFE system 10 could be modified to support video on demand and broadcast media through additional cabling or circuitry, such modification would disadvantageously increase the weight of the aircraft.
Hence, it would be advantageous to create a digital network which eliminates the above-cited disadvantages. The topology of the digital network should be able to support real-time broadcasting of media as well as video on demand.